Influence of adsorption kinetics on chemomechanically enhanced hard rock drilling

Abstract

To enhance the efficiency of diamond bit drilling into hard rocks by means of chemomechanically active additives, several not-so-obvious factors must be taken into account. These include polarity and concentration of surfactant, mode of diamond failure and rate of adsorption of the active species onto the rock under the bit. To evaluate the latter factor, Westerly granite was drilled with diamond bits ranging in size from 0.6 to 6 cm at rotational speeds ranging from 50 to 5000 rpm using aqueous concentrations of Aerosol C-61, a cationic surfactant, ranging from 10⁻⁴ to 10⁻²moll⁻¹. The results reveal that rotational speed has a strong effect on the additive-enhanced diamond life, with maxima appearing under conditions suggesting that, for higher bit speeds, the isoelectric point of the rock effectively occurs at surfactant concentrations greater than those determined under static conditions. The results also demonstrate the possibility of utilizing laboratory-scale drilling tests to inexpensively simulate field-scale tests of potentially useful, bit wear-reducing surfactants.